Method Of Electrical Power Transmission



(No Model.)

N. TESLA. METHOD OF ELECTRICAL POWER TRANSMISSION. No. 405,859. I Patented June 25, 1889.

UNITED STATES PATENT OFFICE.

NIKOLA TESLA, OF NEWV YORK, N. Y., ASSIGNOR TO THE TESLA ELECTRIC COMPANY, OF SAME PLACE.

METHOD OF ELECTRICAL POWER TRANSMISSION.

- SPECIFICATION forming part of Letters Patent No. 405,859, dated June 25, 1889.

,, Application filed March 14, 1889. Serial No. 308,251. (No model.)

T at whom it may concern: In carrying out my present inventionl con- Be it known that I, NIKOLA TEsLA, a substruct a generator with two coils or sets of ject of the Emperor of Austria, from Smilj an, coils and a motor with corresponding energiz- Lika, border country of Austria-Hungary, reing coils or sets of coils. By means of two 5 5 siding at New York, in the county and State line-Wires one terminal of each generator-coil of New York, have invented certain new and or set of coils is connected to one terminal of useful Improvements in Methods of Electrical its corresponding motor-coil or set of coils, Power Transmission, of which the following while the opposite terminals of the generatoris a specification, reference being had to the' coils are joined together and likewise those of 60 [0 drawing accompanying and forming a part the motor.

of the same. To start the motor I establish temporarily This application is for a specific method of an electrical connection between the points of transmitting power electrically, shown and connection between the coils in the generator described in, and covered broadly by the and those in the motor, so that the system 6 5 claims of, an application filed by me February becomes an ordinary double-circuit system 18, 1889, No. 300,220. identical with that described in my patent, As is well known, certain forms of alternat- No. 390,413, of October 2,1888, except that the ing-current machines have the property, when generator and motor are constructed in any connected in circuit with an alternating-curwell-known way with a strong tendency to 70 2o rent generator, of running as a motor in synsynchronize. \Vhen by this plan of connecchronism therewith; but, while the alternating tion the motor has attained the desired speed, current will run the motor after it has atthe earthconnection is severed, by which t ained a rate of speed synchronous with that means the system becomes an ordinary sin gleof the generator, it will not start it; hence, in circuit synchronizing system. all instances heretofore where these syn- In the drawing I have illustrated this chronizing motors, as they are termed, have method by a diagram. been run, some means have been employ ed to Let G represent an ordinary alternating-curbring the motors up to synchronism with the rent generator having four field-poles A, pergenerator, or approximately so, before the manently or artificially magnetized, and an 80 o alternating current of the generator is applied armature wound with two coils C connected to drive them. In some instances mechanical together in series.

appliances have been. utilized for this pur- Let M represent an alternating-current m0- pose. In others special and complicated tor with, say, four poles D, the coils on which forms of motor have been constructed. are connected in pairs and the pairs connected 8 5 3 5 My present invention is an improvement in in series. The motor-armature should have methods of operating these motors and inpolar projections and closed coils E. volves a new and improved plan of bringing From the common joint or union between the motor up to the proper rate of speed, that the two coils or sets of coils of both the genit may be run in synchronism with the generator and motor an earth-connection F is es 9o eraton tablished, while the terminals or ends of the The expression synchronism with the gensaid coils or circuits which they form are conorator is used herein in its ordinary acceptanected to the line-conductors H II. tion-that is to say, a motor is said to syn- Assuming that the motor is a synchronizing chronize with the generator when it preserves motor, or one that has the capability of run- 5 a certain relative speed determined by its ning in synchronism with the generator, but

number of poles and the number of alternanot of starting, it may be started by the abovetions produced per revolution of the gener described plan by closing the ground-connecator. Its actual speed, therefore, may be tion from both generator and motor. The faster or slower than that of the generator, system thus becomes one with a two circuit T00 but it is said to be synchronous so long as itgenerator and motor, the ground forming a preserves the same relative speed. common return for the currents in the two wires II II. \Vhen by this arrangement of circuits the motor is brought to speed, the ground-connection is broken between the generator or motor or both and ground, switches K K being employed for this purpose. The motor then runs as a synchronizing motor.

This system is capable of various useful applications which it is not necessary to describe in detail but it will be enough to say that the convertibility of the system from double circuit to single circuit is a feature in itself of great value and utility.

I do not wish to be understood as confining myself to the precise arrangement or order of connections herein. set forth, as these may be obviously varied in many respects.

Vhat I claim is-- 1. The method of operating synchronizing motors herein described, which consists in electrically connecting intermediate points of the inducing-circuit of the generator and the energizii'lg-circuit of the motor until the motor has reached a desired speed and then interrupting such connection, as set forth.

2. The method herein described of starting or operating synchronizing motors, which conin electrically connecting intermediate points of the inducing-cirmlit of the generator and the energiZing-circuit of the motor to earth until the motor has reached the desired speed and then interrupting either or both of the ground-connections, as set forth.

N IKOLA TESIA.

\Vitnesses:

Emvixnn T. Evan s, E. G. Urs'rrLL. 

